BEOL electrical fuse

ABSTRACT

An electrode structure is located at least partially in a via opening having a small feature size and containing a fuse element which is composed of a fuse element-containing seed layer that is subjected to a reflow anneal. The electrode structure is composed of a material having a higher electromigration (EM) resistance than the material that provides the fuse element. Prior to programming, the fuse element is present along sidewalls and a bottom wall of the electrode structure. After programming, a void is formed in the fuse element along at least one sidewall of the electrode structure and the resistance of the device will increase sharply.

BACKGROUND

The present application relates to back-end-of-the-line (BEOL) electrical fuses (eFuses) and a method of forming the same.

eFuses are used in semiconductor industry to implement array redundancy, field programmable arrays, analog component trimming circuits and even as chip identification circuits. Dog-bone shaped eFuses containing a fuse link are known. In such conventional dog-bone shaped eFuses, the fuse link dimension is limited by the allowable photolithographic minimal dimensions.

While eFuses are thus desirable within semiconductor device design and fabrication and provide an essential tool for cost effective and efficient semiconductor device design and fabrication, eFuses are not entirely without problems. For example, programming of prior art eFuses typically takes a substantial amount of current, which is undesirable in current technology node devices using low driving current. In addition, programming transistors takes up space in a semiconductor chip as well as power consumption.

There is a need to provide BEOL eFuses in which the fuse link is much smaller than conventional photolithographic minimum dimensions and thus the amount of electrical current that is needed to blow the eFuse can be substantially reduced as compared to a conventional eFuse design.

SUMMARY

An electrode structure is located at least partially in a via opening having a small feature size and containing a fuse element which is composed of a fuse element-containing seed layer that is subjected to a reflow anneal. The electrode structure is composed of a material having a higher electromigration (EM) resistance than the material that provides the fuse element. Prior to programming, the fuse element is present entirely along sidewalls and a bottom wall of the electrode structure. After programming, a void is formed in the fuse element along at least one sidewall of the electrode structure and the resistance of the device will increase sharply.

In one aspect of the present application, a structure is provided. In one embodiment, the structure includes an interconnect level including at least one electrically conductive structure embedded in an interconnect dielectric material layer. A dielectric material layer having a via opening is located on the interconnect level, wherein the via opening physically exposes a surface of the at least one electrically conductive structure. An electrode structure is present in at least the via opening. In accordance with the present application, a fuse element is located beneath and along sidewalls of the electrode structure that is present in the via opening, and the electrode structure is composed of a material having a higher electromigration (EM) resistance than the fuse element. A metal-containing structure is located directly on at least the electrode structure.

In another embodiment, the structure includes an interconnect level including at least one electrically conductive structure embedded in an interconnect dielectric material layer. A dielectric material layer having a via opening is located on the interconnect level, wherein the via opening physically exposes a surface of the at least one electrically conductive structure. An electrode structure is present in at least the via opening. In accordance with the present application, a fuse element is located beneath the electrode structure that is present in the via opening, the fuse element having a void that is present along at least one sidewall of the electrode structure that is present in the via opening, and the electrode structure is composed of a material having a higher electromigration (EM) resistance than the fuse element. A metal-containing structure is located directly on at least the electrode structure.

In another aspect of the present application, a method of forming a structure is provided. In one embodiment, the method includes forming an interconnect level including at least one electrically conductive structure embedded in an interconnect dielectric material layer. Next, a dielectric material layer having a via opening is formed on the interconnect level, wherein the via opening physically exposes a surface of the at least one electrically conductive structure. A fuse element-containing layer is then formed on the dielectric material layer and within the via opening by depositing a fuse element-containing seed layer and then subjecting the fuse element-containing seed layer to a reflow anneal. Next, an electrode material layer is formed on the fuse element-containing layer. At least a portion of the electrode material layer and a portion of the fuse element-containing layer that are present outside of the via opening are removed, while maintaining another portion of the electrode material layer and another portion of the fuse element-containing material layer in the via opening. Next, a metal-containing structure is formed on a remaining portion of the electrode material layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an exemplary structure that can be employed in accordance with an embodiment of the present application, wherein the exemplary structure includes a lower interconnect level including at least one first electrically conductive structure embedded in a first interconnect dielectric material layer, a dielectric capping layer, an upper second interconnect level including at least one second electrically conductive structure embedded in a second interconnect dielectric material layer and contacting a surface of the at least one first electrically conductive structure, and a dielectric material layer.

FIG. 2 is a cross sectional view of the exemplary structure of FIG. 1 after forming a via opening within the dielectric material layer which physically exposes one of the second electrically conductive structures embedded in the second interconnect dielectric material layer.

FIG. 3 is a cross sectional view of the exemplary structure of FIG. 2 after forming a diffusion barrier material layer on the dielectric material layer and within the via opening.

FIG. 4 is a cross sectional view of the exemplary structure of FIG. 3 after forming a fuse element-containing seed layer on the diffusion barrier material layer.

FIG. 5 is a cross sectional view of the exemplary structure of FIG. 4 after performing a reflow anneal in which the fuse element-containing seed layer is subject to reflow to provide a fuse element-containing layer.

FIG. 6 is a cross sectional view of the exemplary structure of FIG. 5 after forming an electrode material layer on the fuse element-containing layer.

FIG. 7 is a cross sectional view of the exemplary structure of FIG. 6 after performing a planarization process to form an electrode structure in the via opening formed in the dielectric material layer, wherein a fuse element composed of a remaining portion of the fuse element-containing layer is located beneath and along sidewalls of the electrode structure.

FIG. 8 is a cross sectional view of the exemplary structure of FIG. 7 after forming a third interconnect dielectric material layer.

FIG. 9 is a cross sectional view of the exemplary structure of FIG. 8 after forming an opening in the third interconnect dielectric material layer that physically exposes the electrode structure and the fuse element.

FIG. 10A is a cross sectional view of the exemplary structure of FIG. 9 after forming a metal-containing structure in the opening formed in the third interconnect dielectric material layer and prior to programming the structure.

FIG. 10B is a cross sectional view of a portion of the exemplary structure of FIG. 10A during programming.

FIG. 10C is a cross sectional view of a portion of the exemplary structure of FIG. 10A during programming.

FIG. 10D is a cross sectional view of a portion of the exemplary structure of FIG. 10A after programming in which a void is formed in the fuse element along at least one sidewall of the electrode structure.

FIG. 11 is a cross sectional view of the exemplary structure of FIG. 6 after forming a metal-containing layer on the electrode material layer.

FIG. 12 is a cross sectional view of the exemplary structure of FIG. 11 after patterning the metal-containing layer, the electrode metal layer, the fuse element-containing layer, and the diffusion barrier material layer to provide a patterned structure.

FIG. 13 is a cross sectional view of the exemplary structure of FIG. 12 after forming a third interconnect dielectric material layer laterally adjacent to each sidewall of the patterned structure.

DETAILED DESCRIPTION

The present application will now be described in greater detail by referring to the following discussion and drawings that accompany the present application. It is noted that the drawings of the present application are provided for illustrative purposes only and, as such, the drawings are not drawn to scale. It is also noted that like and corresponding elements are referred to by like reference numerals.

In the following description, numerous specific details are set forth, such as particular structures, components, materials, dimensions, processing steps and techniques, in order to provide an understanding of the various embodiments of the present application. However, it will be appreciated by one of ordinary skill in the art that the various embodiments of the present application may be practiced without these specific details. In other instances, well-known structures or processing steps have not been described in detail in order to avoid obscuring the present application.

It will be understood that when an element as a layer, region or substrate is referred to as being “on” or “over” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly over” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “beneath” or “under” another element, it can be directly beneath or under the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly beneath” or “directly under” another element, there are no intervening elements present.

Referring first to FIG. 1, there is illustrated an exemplary structure that can be employed in accordance with an embodiment of the present application. The exemplary structure includes a lower (or first) interconnect level, L_(n), including at least one first electrically conductive structure 12 embedded in a first interconnect dielectric material layer 10, a dielectric capping layer 14, an upper (or second) interconnect level, L_(n+1), including at least one second electrically conductive structure 18D embedded in a second interconnect dielectric material layer 16 and contacting a surface of the at least one first electrically conductive structure 12, and a dielectric material layer 20. In accordance with the present application, n is 0 or an integer starting from 1. When n is 0, the lower interconnect level, L_(n), is omitted and replaced with a front-end-of-the-line structure that includes a semiconductor substrate that contains a plurality of semiconductor devices formed therein or thereupon.

When present, the lower interconnect level, L_(n), includes a first interconnect dielectric material layer 10 that includes at least one first electrically conductive structure 12 embedded therein. A diffusion barrier liner (not shown) can also be present that surrounds the sidewalls and the bottom wall (i.e., bottommost surface) of the at least one first electrically conductive structure 12 which is embedded in the first interconnect dielectric material layer 10. The first electrically conductive structure 12 is typically an electrically conductive via structure.

The first interconnect dielectric material layer 10 of the lower interconnect level, L_(n), can be composed of an inorganic dielectric material or an organic dielectric material. In some embodiments, the first interconnect dielectric material layer 10 may be porous. In other embodiments, the first interconnect dielectric material layer 10 may be non-porous. Examples of suitable dielectric materials that may be employed as the first interconnect dielectric material layer 10 include, but are not limited to, silicon dioxide, undoped or doped silicate glass, silsesquioxanes, C doped oxides (i.e., organosilicates) that include atoms of Si, C, O and H, theremosetting polyarylene ethers or any multilayered combination thereof. The term “polyarylene” is used in this present application to denote aryl moieties or inertly substituted aryl moieties which are linked together by bonds, fused rings, or inert linking groups such as, for example, oxygen, sulfur, sulfone, sulfoxide, or carbonyl.

The first interconnect dielectric material layer 10 may have a dielectric constant (all dielectric constants mentioned herein are measured relative to a vacuum, unless otherwise stated) that is about 4.0 or less. In one embodiment, the first interconnect dielectric material layer 10 has a dielectric constant of 2.8 or less. These dielectrics generally having a lower parasitic cross talk as compared to dielectric materials whose dielectric constant is greater than 4.0.

The first interconnect dielectric material layer 10 may be formed by a deposition process such as, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) or spin-on coating. The first interconnect dielectric material layer 10 may have a thickness from 50 nm to 250 nm. Other thicknesses that are lesser than 50 nm, and greater than 250 nm can also be employed in the present application.

After providing the first interconnect dielectric material layer 10, at least one opening (not shown) is formed into the first interconnect dielectric material layer 10; each opening will house a first electrically conductive structure 12 and, if present, the diffusion barrier liner. The at least one opening in the first interconnect dielectric material layer 12 is typically a via opening. The at least one opening can be formed by lithography and etching.

In some embodiments, a diffusion barrier material is then formed within the at least one opening and on an exposed topmost surface of the first interconnect dielectric material layer 10; the diffusion barrier material will provide the diffusion barrier liner mentioned above. The diffusion barrier material may include Ta, TaN, Ti, TiN, Ru, RuN, RuTa, RuTaN, W, WN or any other material that can serve as a barrier to prevent a conductive material from diffusing there through. The thickness of the diffusion barrier material may vary depending on the deposition process used as well as the material employed. In some embodiments, the diffusion barrier material may have a thickness from 2 nm to 50 nm; although other thicknesses for the diffusion barrier material are contemplated and can be employed in the present application as long as the diffusion barrier material does not entirety fill the opening. The diffusion barrier material can be formed by a deposition process including, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, chemical solution deposition or plating.

In some embodiments, an optional plating seed layer (not specifically shown) can be formed on the surface of the diffusion barrier material. In some embodiments, the optional plating seed layer is not needed. The optional plating seed layer is employed to selectively promote subsequent electroplating of a pre-selected conductive metal or metal alloy. The optional plating seed layer may be composed of Cu, a Cu alloy, Ir, an Ir alloy, Ru, a Ru alloy (e.g., TaRu alloy) or any other suitable noble metal or noble metal alloy having a low metal-plating overpotential. Typically, Cu or a Cu alloy plating seed layer is employed, when a Cu metal is to be subsequently formed within the at least one opening. The thickness of the optional plating seed layer may vary depending on the material of the optional plating seed layer as well as the technique used in forming the same. Typically, the optional plating seed layer has a thickness from 2 nm to 80 nm. The optional plating seed layer can be formed by a conventional deposition process including, for example, CVD, PECVD, ALD, or PVD.

Next, an electrically conductive metal or metal alloy is formed into each opening and, if present, atop the diffusion barrier material. The electrically conductive metal or metal alloy provides the first electrically conductive structure 12 of the present application. The electrically conductive metal or metal alloy can be composed of copper (Cu), aluminum (Al), tungsten (W), or an alloy thereof such as, for example, a Cu—Al alloy. The electrically conductive metal or metal alloy can be formed utilizing a deposition process such as, for example, CVD, PECVD, sputtering, chemical solution deposition or plating. In one embodiment, a bottom-up plating process is employed in forming the electrically conductive metal or metal alloy. In some embodiments, the electrically conductive metal or metal alloy is formed above the topmost surface of the first interconnect dielectric material layer 10.

Following the deposition of the electrically conductive metal or metal alloy, a planarization process such as, for example, chemical mechanical polishing (CMP) and/or grinding, can be used to remove all electrically conductive metal or metal alloy (i.e., overburden material) that is present outside each of the openings forming the first electrically conductive structure 12. The planarization stops on a topmost surface of the first interconnect dielectric material layer 10. Thus, and if present, the planarization process also removes the diffusion barrier material from the topmost surface of the first interconnect dielectric material layer 10. The remaining portion of the diffusion barrier material that is present in the at least one opening is referred to herein as the diffusion barrier liner, while the remaining first electrically conductive metal or metal alloy that is present in the at least one opening may be referred to as the first electrically conductive structure 12. In some embodiments, the planarization process is omitted. Collectively, the first interconnect dielectric material layer 10, each optional diffusion barrier liner, and each first electrically conductive structure 12 define the lower interconnect level, L_(n), of the present application.

Next, and in some embodiments, a dielectric capping layer 14 can be formed on the physically exposed topmost surface of the lower interconnect level, L_(n), of the present application. In some embodiments, the dielectric capping layer 14 can be omitted. When present, the dielectric capping layer 14 may include any dielectric material such as, for example, silicon carbide (SiC), silicon nitride (Si₃N₄), silicon dioxide (SiO₂), a carbon doped oxide, a nitrogen and hydrogen doped silicon carbide (SiC(N,H)) or a multilayered stack of at least one of the aforementioned dielectric capping materials. The dielectric material that provides the dielectric capping layer 14 can be formed utilizing a deposition process such as, for example, CVD, PECVD, ALD, chemical solution deposition or evaporation. When present, the dielectric capping layer 14 typically has a thickness from 10 nm to 100 nm; although other thicknesses that are different from the exemplary thickness range can be used as the thickness of the dielectric capping layer 14.

Next, the second interconnect dielectric material layer 16 is formed above the lower interconnect level, L_(n). The second interconnect dielectric material layer 16 may include one of the interconnect dielectric materials mentioned above for the first interconnect dielectric material layer 10. In some embodiments, the second interconnect dielectric material layer 16 includes a same interconnect dielectric material as the first interconnect dielectric material layer 10. In other embodiments, the second interconnect dielectric material layer 16 includes a different interconnect dielectric material than the first interconnect dielectric material layer 10. The second interconnect dielectric material layer 16 may be porous or non-porous, have a thickness within the thickness range of the first interconnect dielectric material layer 10, and be formed utilizing one of the deposition processes used in providing the first interconnect dielectric material layer 10.

Next, at least one opening (not shown) having a width that is greater than the width of the first electrically conductive structure 12 can then be formed into the second interconnect dielectric material layer 16. During or, after, the forming of the at least one opening, the dielectric capping layer 14 is opened to physically expose a surface of the first electrically conductive structure 12. Other openings (not shown) can be formed into the second interconnect dielectric material layer 16 which may, or may not extend, into the first interconnect dielectric material layer 10. In embodiments in which n is 0, some of the openings that are formed into the second interconnect dielectric material layer 16 can physically expose a conductive material or conductive region of one of the semiconductor devices that is formed upon or within a semiconductor substrate. The at least one opening is formed by lithography and etching.

The at least one opening that is formed into the second interconnect dielectric material layer 16 is processed to include at least a second electrically conductive structure. In FIG. 1, elements 18A, 18B, 18C and 18D represent such second electrically conductive structures. As is shown, at least one of the second electrically conductive structures, e.g., second electrically conductive structure 18D, has a surface that contacts a surface of the first electrically conductive structure 12, a conductive structure or a conductive region.

The second electrically conductive structures 18A, 18B, 18C and 18D may include one of the electrically conductive metals or metal alloys mentioned above for the first electrically conductive structure 12. In one embodiment, the second electrically conductive structures 18A, 18B, 18C and 18D may include a same electrically conductive metal or metal alloy as the first electrically conductive structure 12. In another embodiment, the second electrically conductive structures 18A, 18B, 18C and 18D may include a compositionally different electrically conductive metal or metal alloy than the first electrically conductive structure 12. The second electrically conductive structures 18A, 18B, 18C and 18D can be formed utilizing the same technique as mentioned above for forming the first electrically conductive structure. A diffusion barrier liner, as defined above, may or may not be formed along the sidewalls and along the bottom wall of each second electrically conductive structure.

Next, dielectric material layer 20 is formed. Dielectric material layer 20 can be composed of any dielectric material including one of the dielectric materials mentioned above for the first interconnect dielectric material layer 10 or the dielectric capping layer 14. The dielectric material layer 20 can be formed by a deposition process such as, for example, CVD, PECVD, ALD, chemical solution deposition or evaporation. The dielectric material layer 20 typically has a thickness from 50 nm to 500 nm; although other thicknesses that are different from the exemplary thickness range can be used as the thickness of the dielectric material layer 20.

Referring now to FIG. 2, there is illustrated the exemplary structure of FIG. 1 after forming a via opening 22 within the dielectric material layer 20 which physically exposes one of the second electrically conductive structures, i.e., second electrically conductive structure 18D, embedded in the second interconnect dielectric material layer 16. The via opening 22 can be formed by lithography and etching. Lithography includes applying a photoresist material over a material or material stack to be patterned, exposing the photoresist material to a pattern of irradiation, and developing the exposed photoresist material. The etching may include an anisotropic etch etching process such as, for example, reactive ion etching. The via opening 22 has a width that is less than the width of the underlying second electrically conductive structure 18D. In one example, the via opening 22 has a width from 10 nm to 200 nm.

Referring now to FIG. 3, there is illustrated the exemplary structure of FIG. 2 after forming a diffusion barrier material layer 24 on the dielectric material layer 20 and within the via opening 22. In some embodiments, the formation of the diffusion barrier material may be omitted. The diffusion barrier material layer 24 is composed of a diffusion barrier material as defined above. Some examples of diffusion barrier materials that can provide the diffusion barrier material layer 24 include, but are not limited to, metal diffusion barriers such as Ta, Ti, Co, Ru, W, Ir, Rh or alloys thereof, or metal nitride diffusion barriers such as TaN, TiN, RuN, RuTaN, or WN.

The thickness of the diffusion barrier material layer 24 may vary depending on the deposition process used as well as the material employed. In some embodiments, the diffusion barrier material layer 24 may have a thickness from 2 nm to 50 nm; although other thicknesses for the diffusion barrier material layer 24 are contemplated and can be employed in the present application as long as the diffusion barrier material layer 24 does not entirely fill the via opening 22. The diffusion barrier material layer 24 can be formed by a deposition process including, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, chemical solution deposition or plating.

Referring now to FIG. 4, there is illustrated the exemplary structure of FIG. 3 after forming a fuse element-containing seed layer 26 on the diffusion barrier material layer 24; when the diffusion barrier material layer is omitted, the fuse element-containing seed layer 26 is formed on the structure shown in FIG. 2. The fuse element-containing seed layer 26 that is employed in the present application is composed of a fuse element material that can be reflowed during a subsequently performed reflow anneal. Examples of fuse element materials that can be employed in the present application include, but are not limited to, Si, Cu, Al, SiN, CuN, AlN, or an ally including at least two of Si, Cu and Al (i.e., a Cu—Al alloy). The thickness of the fuse element-containing seed layer 26 may vary depending on the deposition process used as well as the material employed. In some embodiments, the fuse element-containing seed layer 26 may have a thickness from 2 nm to 500 nm; although other thicknesses for the fuse element-containing seed layer 26 are contemplated and can be employed in the present application as long as the fuse element-containing seed layer 26 does not entirely fill the via opening 22. The fuse element-containing seed layer 26 can be formed by a deposition process including, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, or plating. In one embodiment, the fuse element-containing seed layer 26 is composed of high-purity (greater than 99.999%) Cu that is deposited using electrochemical plating.

Referring now to FIG. 5, there is illustrated the exemplary structure of FIG. 4 after performing a reflow anneal in which the fuse element-containing seed layer 26 is subject to reflow. The reflow anneal may include a furnace anneal or a laser anneal; laser annealing is typically performed for a shorter period of time than furnace anneal. The reflow anneal is performed at a temperature that melts the fuse material that provides the fuse element-containing seed layer 26 such that the same flows into and fills the via opening 22. As is known to those skilled in the art, capillary force/surface tension is the driving force pulling the fuse element-containing seed layer 26 into the via opening 22.

In one example, and when the reflow anneal is performed in a furnace, the ‘furnace’ reflow anneal can be performed at a temperature from 60° C. to 500° C. for a time period from 10 minutes to 6 hours. In another example, and when the reflow anneal is performed using a laser, the ‘laser’ reflow anneal is performed at a temperature from 400° C. to 1000° C. for a time period of a few nanoseconds.

The reflowed fuse element-containing seed layer 26 can be referred to herein as a fuse element-containing layer 26A. The fuse element-containing layer 26A has a first region that is located in the via opening 22 that is thicker than a second region of the fuse element-containing layer 26A that is located predominately outside the via opening 22; a portion of the thinner second region of the fuse element-containing layer 26A is present along an upper portion of the sidewalls of the via opening 22 as shown in FIG. 5.

Referring now to FIG. 6, there is illustrated the exemplary structure of FIG. 5 after forming an electrode material layer 28 on the fuse element-containing layer 26A. The electrode material layer 28 is composed of a material (i.e., an electrically conductive material) that has a higher electromigration (EM) resistance than the fuse element material that provides the fuse element-containing layer 26A. The electrode material layer 28 can be composed of an electrically conductive metal, an electrically conductive metal alloy or an electrically conductive metal nitride. Exemplary materials for the electrode material layer 28 include Ta, Ti, W, Co, Ru, Ir or Rh, or their nitrides or alloys.

The electrode material layer 28 may be formed utilizing a deposition process including, for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, chemical solution deposition or plating. The electrode material layer 28 may have a thickness from 5 nm to 100 nm; although other thicknesses besides the exemplary thickness range can be used as the thickness of the electrode material layer 28.

Referring now to FIG. 7, there is illustrated the exemplary structure of FIG. 6 after performing a planarization process to form an electrode structure 28S in the via opening 22 formed in the first dielectric material layer 20, wherein a fuse element 26S composed of a remaining portion of the fuse element-containing layer 26A is located beneath and along sidewalls of the electrode structure 28S.

The planarization process, which can include, for example, chemical mechanical polishing (CMP) and/or grinding, removes the electrode material layer 28, the fuse element-containing layer 26A and, if present, the diffusion barrier material layer 24 that is located outside the via opening 22. Portions of the electrode material layer 28, the fuse element-containing layer 26A and, if present, the diffusion barrier material layer 24 remain in the via opening 22. The remaining portion of the electrode material layer 28 that is present in the via opening 22 is referred to herein as the electrode structure 28S, the remaining portion of the fuse element-containing layer 26A that remains in the via opening 22 is referred to herein as the fuse element 26S, and, when present, the remaining portion of the diffusion barrier material layer 24 that remains in the via opening 22 is referred to as a diffusion barrier liner 24L.

The fuse element 26S has a thin portion 26P that is located on sidewalls of the electrode structure 28S. If present, the diffusion barrier liner 24L is U-shaped. The term “U-shaped” is used throughout the present application to denote that a material has a horizontal portion in which a vertical portion extends upwards from each end of the horizontal portion.

The electrode structure 28S has a topmost surface that is coplanar with a topmost surface of each of the dielectric material layer 20, the thin portions 26P of the fuse element 26S, and, if present, the vertical portions of the diffusion barrier layer 24L.

Referring now to FIG. 8, there is illustrated the exemplary structure of FIG. 7 after forming a third interconnect dielectric material layer 30. The third interconnect dielectric material layer 30 is composed of one of the dielectric materials mentioned above for the first interconnect dielectric material layer 10. In one embodiment, the third interconnect dielectric material layer 30 is composed of a same dielectric material as the first interconnect dielectric material layer 10 and/or the second interconnect dielectric material layer 16. In another embodiment, the third interconnect dielectric material layer 30 is composed of a different dielectric material than the first interconnect dielectric material layer 10 and/or the second interconnect dielectric material layer 16.

The third interconnect dielectric material layer 30 may be formed using one of the deposition techniques mentioned above for forming the first interconnect dielectric material layer 10. The third interconnect dielectric material layer 30 may have a thickness from 50 nm to 900 nm; although other thicknesses besides the exemplary thickness range can be used as the thickness of the third interconnect dielectric material layer 30.

Referring now to FIG. 9, there is illustrated the exemplary structure of FIG. 8 after forming an opening 32 in the third interconnect dielectric material layer 30 that physically exposes the electrode structure 28S and the fuse element 26S. The opening 32 that is formed into the third interconnect dielectric material layer 30 has a width that is generally greater than the width of the via opening 22 provided to the dielectric material layer 20. In one example, the opening 32 that is formed into the third interconnect dielectric material layer 30 has a width from 15 nm to 400 nm. The opening 32 can be formed by lithography and etching as defined above for forming the via opening 22 into the dielectric material layer 20.

Referring now to FIG. 10A, there is illustrated the exemplary structure of FIG. 9 after forming a metal-containing structure 34S in the opening 32 formed in the third interconnect dielectric material layer 30. The metal-containing structure 34S is composed of at least one layer of an electrically conductive metal-containing material. The metal-containing structure 34S can be formed by depositing a layer of the electrically conductive metal-containing material or a material stack of electrically conductive metal-containing materials and then subjecting the deposited electrically conductive metal-containing material or deposited material stack of electrically conductive metal-containing materials to a planarization process such as, for example, chemical mechanical polishing (CMP) and/or grinding. The metal-containing structure 34S typically has a topmost surface that is coplanar h a topmost surface of the third interconnect dielectric material layer 30, and a bottommost surface that is in direct physical contact with at least the electrode structure 28S.

In one embodiment, the metal-containing structure 34S is composed of one of the electrically conductive metals or metal alloys as mentioned above for the first electrically conductive structure 12. In another embodiment, the metal-containing structure 34S is composed of a stack including one of the electrically conductive metals or metal alloys as mentioned above for the first electrically conductive structure 12.

Notably, FIG. 10A illustrates an exemplary structure of the present application prior to programming (i.e., blowing the fuse element) that includes an interconnect level, L_(n+1), including at least one electrically conductive structure 18D embedded in an interconnect dielectric material layer 16. A dielectric material layer 20 having a via opening 22 is located on the interconnect level, L_(n+1), wherein the via opening 22 physically exposes a surface of the at least one electrically conductive structure 18D. A void-less electrode structure 28S is present in at least the via opening 22, wherein a fuse element 26S is located beneath and along sidewalls of the electrode structure 28S that is present in the via opening 22; no void is present in the fuse element 26S at this point. A metal-containing structure 34S is located directly on the electrode structure 28S; the metal-containing structure 34S may extend onto a surface of the fuse element 26S and a surface of the dielectric material layer 20. In this embodiment, the electrode structure 28S has a topmost surface that is coplanar with at least a topmost surface of the fuse element 26S as well as dielectric material layer 20. The exemplary structure of FIG. 10A has a resistance. R1, that is constant over time.

Referring now to FIGS. 10B and 10C, there are shown a portion of the exemplary structure of FIG. 10A during programming. FIG. 10B shows an embodiment in which electrons, e⁻, are moving in a vertically upward path, while FIG. 10C shows an embodiment in which electrons, e⁻, are moving in a vertically downward path. The exemplary structures of FIGS. 10B and 10C both have a resistance that is exponentially increasing from R1 over time.

Referring now to FIG. 10D, there is shown a portion of the exemplary structure of FIG. 10A after programming in which a void, V, is formed in the fuse element 26S along at least one sidewall of the electrode structure 28S. Although not shown, other voids may form along the other sidewalls electrode structure 28S. After programming, the structure of FIG. 10D has a resistance, R2, which is constant over time, wherein R2 is greater than R1. In some embodiments, R2/R1 is greater than 10. Programming can be achieved utilizing techniques well known in the e-Fuse art. For example, programming can be achieved by pushing higher electrical current to initiate electromigration failure.

In the embodiment described above, the fuse element 26A can be ring-shaped, and the ring-shaped fuse element 26A surrounds the electrode structure 28S.

Referring now to FIG. 11, there is illustrated the exemplary structure of FIG. 6 after forming a metal-containing layer 34 on the electrode material layer 28. The metal-containing layer 34 is composed of an electrically conductive metal-containing material or electrically conductive metal-containing material stack as defined above for the metal-containing structure 34S. The metal-containing layer 34 can be formed by utilizing one or more deposition processes such, as for example, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD), sputtering, chemical solution deposition or plating. The metal-containing layer 34 may have a thickness from 5 nm to 500 nm; although other thicknesses besides the exemplary thickness range can be used as the thickness of the metal-containing layer 34.

Referring now to FIG. 12, there is illustrated the exemplary structure of FIG. 11 after patterning the metal-containing layer 34, the electrode metal layer 28, the reflowed fuse element-containing seed layer (i.e., the fuse element-containing layer 26A), and, if present, the diffusion barrier material layer 24 to provide a patterned structure (24L, 26S, 28S, 34S).

In the embodiment illustrated in FIG. 12, the patterned structure includes, from bottom to top, a remaining portion of the diffusion barrier material layer (hereinafter diffusion barrier liner 24L), a remaining portion of the fuse element-containing 26A (hereinafter fuse element 26S), a remaining portion of the electrode metal layer 28 (hereinafter electrode structure 28S), and a remaining portion of the metal-containing layer 34 (hereinafter metal-containing structure 34S). The diffusion barrier liner 24L may be omitted from the patterned structure of this embodiment of the present application. Unlike the previous embodiment of the present application in which the diffusion barrier liner 24L (if present), the fuse element 26S, and the electrode structure 28S were confined in via opening 22 (see, for example, FIG. 12), the diffusion barrier liner 24L (when present), the fuse element 26S, and the electrode structure 28S provided in this example include a portion that is located outside the via opening 22.

The patterning of the metal-containing layer 34, the electrode metal layer 28, the fuse element-containing layer 26A, and, if present, the diffusion barrier material layer 24 can be performed by lithography and etching.

Referring now to FIG. 13, there is illustrated the exemplary structure of FIG. 12 after forming a third interconnect dielectric material layer 30 laterally adjacent to each sidewall of the patterned structure (24L, 26S, 28S, 34S). The third interconnect dielectric material layer 30 is composed of one of the dielectric materials mentioned above for the first interconnect dielectric material layer 10. In one embodiment, the third interconnect dielectric material layer 30 is composed of a same dielectric material as the first interconnect dielectric material layer 10 and/or the second interconnect dielectric material layer 16. In another embodiment, the third interconnect dielectric material layer 30 is composed of a different dielectric material than the first interconnect dielectric material layer 10 and/or the second interconnect dielectric material layer 16.

The third interconnect dielectric material layer 30 may be formed using one of the deposition techniques mentioned above for forming the first interconnect dielectric material layer. Following the deposition of the third interconnect dielectric material layer 30, a planarization process such as, for example, chemical mechanical polishing (CMP) and/or grinding) can be used to provide the exemplary structure shown in FIG. 13. After planarization, the third interconnect dielectric material layer 30 has a topmost surface that is coplanar with a topmost surface of the metal-containing structure 34S of the patterned structure (24L, 26S, 28S, 34S).

Notably, FIG. 13 illustrates an exemplary structure of the present application that includes an interconnect level, L_(n+1), including at least one electrically conductive structure 18D embedded in an interconnect dielectric material layer 16. A dielectric material layer 20 having a via opening 22 is located on the interconnect level, L_(n+1), wherein the via opening 22 physically exposes a surface of the at least one electrically conductive structure 18D. A void-less electrode structure 28S is present in at least the via opening 22, wherein a fuse element 26S is located beneath and along sidewalls of the electrode structure 28S that is present in the via opening 22. At this point of the present application, the structure shown in FIG. 13 is not programmed, and thus no void is present in the fuse element 26S. A metal-containing structure 34S is located directly on the electrode structure 28S. In this embodiment, the electrode structure 28S and the fuse 26S extend outside the via opening 22 and are present atop the dielectric material layer 20. The structure shown in FIG. 13 would have a resistance, R1, which is constant over time. During a programming process, electrons can flow vertically upward or vertically downward through the structure shown in FIG. 13.

Although not shown in any drawing, the structure shown in FIG. 13 can be programmed as described above to provide a void in the fuse element 26S along at least one of the sidewalls of the electrode structure 26S. The resistance, R2, of the structure shown in FIG. 13 after programming would be constant over time and is higher than R1. In some embodiments, R2/R1 is greater than 10.

In any of the embodiments described herein, additional fuse elements and electrode structure can be formed to provide a structure having multiple programming capabilities.

While the present application has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms and details may be made without departing from the spirit and scope of the present application. It is therefore intended that the present application not be limited to the exact forms and details described and illustrated, but fall within the scope of the appended claims. 

What is claimed is:
 1. A structure comprising: an interconnect level including at least one electrically conductive structure embedded in an interconnect dielectric material layer; a dielectric material layer having a via opening located on the interconnect level, wherein the via opening physically exposes a surface of the at least one electrically conductive structure; an electrode structure present in at least the via opening, wherein a fuse element is located beneath and along sidewalls of the electrode structure that is present in the via opening, and wherein the electrode structure is composed of a material having a higher electromigration (EM) resistance than the fuse element; and a metal-containing structure located directly on at least the electrode structure.
 2. The structure of claim 1, further comprising a diffusion barrier liner located in the via opening, wherein the diffusion barrier liner is located along sidewalls and a bottom wall of the fuse element.
 3. The structure of claim 1, wherein the electrode structure has a topmost surface that is coplanar with a topmost surface of the fuse element.
 4. The structure of claim 3, wherein the metal-containing structure is embedded in another interconnect dielectric material layer that is located on the dielectric material layer.
 5. The structure of claim 1, wherein a portion of both the electrode structure and the fuse element extends outside of the via opening and is present above a topmost surface of the dielectric material layer.
 6. The structure of claim 5, wherein the metal-containing structure and the portions of the electrode structure and the fuse element that extend outside of the via opening are embedded in another interconnect dielectric material layer that is located on the dielectric material layer.
 7. The structure of claim 1, wherein the electrode structure is composed of Ta, Ti, W, Co, Ru, Ir or Rh, or their nitrides or alloys.
 8. The structure of claim 7, wherein the fuse element is composed of Si, Cu, Al, SiN, AlN, CuN, or an alloy containing at least two of Si, Cu and Al.
 9. The structure of claim 1, further comprising another interconnect level located beneath the interconnect level, wherein the another interconnect level comprises at least one other electrically conductive structure embedded in another interconnect dielectric material layer, wherein the at least one other electrically conductive structure contacts a surface of the at least one electrically conductive structure embedded in the interconnect dielectric material layer. 